Liquid crystal display device formed on glass substrate having improved efficiency

ABSTRACT

An LCD device includes a displaying unit having a plurality of pixel areas defined by a plurality of gate lines and data lines disposed in longitudinal and transverse directions, a thin film transistor (TFT) formed in each of the pixel areas to be connected to a pixel electrode formed in the pixel area, and a gate pad and a data pad formed on ends of the corresponding gate line and data line; and a dummy region formed on an outer portion of the displaying unit, and including a gate shorting bar and a data shorting bar which are connected to the gate pads and the data pads to apply test signal(s) to the TFTs, wherein at least one of the gate shorting bar and the data shorting bar is a single shorting bar.

[0001] The present application claims the benefit of Korean PatentApplication No. 2001-0088551 filed on Dec. 29, 2001, which is hereinfully incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display device,and particularly, to a liquid crystal display device which improves theefficiency of a glass substrate by integrating shorting bars and therebyminimizing a margin of the liquid crystal panel formed on the glasssubstrate.

[0004] 2. Description of the Background Art

[0005] A liquid crystal display (LCD) device is a transmittive flatpanel display device, and is used in various electric devices such asmobile phones, PDAs and notebook computers. The LCD can be formed as asmall, lightweight and power-efficient device, and can realize a highimage quality. Therefore, the LCD has been researched and developed morethan any other display devices. Moreover, as needs for digital TVs, highimage quality TVs and wall mounted TVs increase, the LCD with a largerdisplay area, which can be used in these TVs, is being researchedactively.

[0006] Generally, LCDs can be divided into a few kinds according to themethods of operating liquid crystal molecules. However, an active matrixthin film transistor LCD is mainly used presently due to its rapidreaction speed and a minimal production of residual images.

[0007]FIG. 1 shows a structure of a general liquid crystal panel 1 inthe above discussed TFT LCD. As shown therein, the liquid crystal panel1 of the TFT LCD comprises a displaying unit 2 on which an image isrealized. A plurality of gate lines 3 and data lines 5 defining aplurality of pixel areas are disposed in longitudinal and transversedirections on the displaying unit 2. A thin film transistor (TFT) 7,which is a switching device, is disposed in each of the pixel areas.Each TFT 7 is switched when a scan signal is input through thecorresponding gate line 3 to pass a signal from the corresponding dataline to the corresponding pixel electrode 9. Also, gate pads 12 and datapads 14 are formed on the ends of the gate lines 3 and data lines 5.Although it is not shown in FIG. 1, a gate driving IC and a data drivingIC are mounted on the outer portions of the liquid crystal panel 1 tosupply signals to the gate lines 3 and to the data lines 5 through thecorresponding gate pads 12 and data pads 14.

[0008] Although it is not shown in FIG. 1 in detail, each thin filmtransistor 7 includes a gate electrode to which a scan signal is appliedfrom the gate driving IC, and being connected to the corresponding gateline 3; a gate insulating layer formed on the gate electrode; asemiconductor layer formed on the gate insulating layer for forming achannel layer as the scan signal is applied to the gate electrode; andsource/drain electrodes formed on the semiconductor layer for applying asignal to the pixel electrode 9. This signal is input through thecorresponding data line 5 from the data driving IC as the channel layeris formed.

[0009] Generally, the liquid crystal panel includes an upper substrateand a lower substrate. The components described above, such as the gatelines, the data lines, the thin film transistors and pixel electrodes,are all formed on the lower substrate. A color filter for realizingcolors is formed on the upper substrate. The upper substrate and thelower substrate are attached and a liquid crystal is injectedtherebetween to complete the liquid crystal display device.

[0010] In the structure of the LCD device constructed as above, the thinfilm transistor is a basic component for driving the LCD device.Therefore, after the thin film transistors are formed on the lowersubstrate, an inspection for identifying whether or not the thin filmtransistors are operated normally should be performed.

[0011] In order to inspect the operation of each thin film transistor, atest signal is applied to the corresponding gate electrode and to thecorresponding source/drain electrodes, and then the voltage on thecorresponding pixel electrode is measured. If there is a voltage changein the pixel electrode, it means that the test signal input through thesource/drain electrodes was successfully applied to the pixel electrodeand the thin film transistor is operating normally. If there is novoltage change in the pixel electrode, it indicates that an error ordefect exists in the thin film transistor.

[0012] Generally, the test signal is input through the gate pad 12 andthe data pad 14 formed on the ends of the gate line 3 and the data line5. An additional wiring is needed to input the test signal.

[0013] Reference numerals 16 (16 a, 16 b) and 18 (18 a, 18 b) shown inFIG. 1 represent bars provided for inspecting the thin film transistors.These bars are also called as ‘shorting bars’. These shorting bars 16and 18 are formed on an outer portion of the displaying unit 2 in theliquid crystal panel 1, where this outer portion of the displaying unit2 is generally called as a ‘dummy region’.

[0014] As shown in FIG. 1, the shoring bars 16 and 18 formed in thedummy region can be divided into gate shorting bars 18 a and 18 b anddata shorting bars 16 a and 16 b. The respective shoring bars are formedin pairs to be connected to respective odd gate pads 12 and odd datapads 14 and to be connected to respective even gate pads 12 and evendata pads 14.

[0015] Also, the shorting bars 18 a and 18 b for the gates are connectedto a gate test signal generating unit 20 to supply the gate test signalsoutput from the gate test signal generating unit 20 to the gate lines 3.The shorting bars 16 a and 16 b for the data lines are connected to adata test signal generating unit 22 to supply the data test signalsoutput from the data test signal generating unit 22 to the data lines 5.

[0016] Generally, a plurality of liquid crystal panels are fabricatedaltogether. That is, a plurality of liquid crystal panels are firstfabricated on a single glass substrate of a large area. Then, this glasssubstrate is processed and cut into multiple sections to producemultiple liquid crystal panels. Therefore, the yield of an LCD device isdependent on how many liquid crystal panels can be fabricated on asingle glass substrate (that is, how efficiently the glass substrate isused).

[0017]FIG. 2 shows an example of a glass substrate 30 on which aplurality of liquid crystal panels (for example, 6 panels) are formed.As shown therein, six liquid crystal panels 1 are provided. Each liquidcrystal panel 1 comprises a displaying unit 2 on which an image isrealized and a dummy region 4 in which the shorting bars 16 and 18 areformed. In this environment, it is difficult to reduce the size of thedisplaying unit 2 having a fixed number of pixels since it requires finepitch technology.

[0018] Therefore, in order to improve the efficiency of the glasssubstrate, it is desirable that the size of the dummy regions 4 of theliquid crystal panels 1 is reduced. However, in the general LCD device,since the gate shorting bars 18 a and 18 b and the data shorting bars 16a and 16 b are formed in pairs, it is very difficult to reduce the sizeof the dummy regions (that is, the margin of the liquid crystal panel).

SUMMARY OF THE INVENTION

[0019] Therefore, an object of the present invention is to provide aliquid crystal display device in which the margin of a liquid crystalpanel is minimized by forming at least one of a gate shorting bar and adata shorting bar using a single line or bar, to maximize the efficiencyof a glass substrate on which the liquid crystal panel is formed.

[0020] Another object of the present invention is to provide a liquidcrystal display device and technique that overcomes problems anddisadvantages of the background art LCD devices.

[0021] To achieve the objects of the present invention, as embodied andbroadly described herein, there is provided a display device comprising:a plurality of pixel areas defined by a plurality of gate lines and aplurality of data lines, and including a thin film transistor formed ineach of the pixel areas; a plurality of gate pads coupled to the gatelines in an outer portion of the display device; a plurality of datapads coupled to the data lines in the outer portion of the displaydevice; and a dummy region disposed in the outer portion of thedisplaying device, and including a gate shorting bar and a data shortingbar which are connected to the gate pads and the data pads,respectively, to apply at least one test signal to the thin filmtransistors, wherein at least one of the gate shorting bar and the datashorting bar is a single shorting bar.

[0022] A test signal generating unit is connected respectively to thegate shorting bar and the data shorting bar to apply the test signal tothe shorting bars. Each of the gate shorting bar and the data shortingbar may be formed using a single line or bar. In another example, thegate shorting bar may be formed using a single line and the datashorting bar may be formed using two lines. In another example, the datashorting bar may be formed using a single line and the gate shorting barmay be formed using two lines.

[0023] The foregoing and other objects, features, aspects and advantagesof the present invention will become more apparent from the followingdetailed description of the present invention when taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0025] In the drawings:

[0026]FIG. 1 is a plane view showing a structure of a general liquidcrystal display (LCD) device;

[0027]FIG. 2 is a view showing a general glass substrate on which aplurality of liquid crystal panels are formed;

[0028]FIG. 3A is a view showing a structure of an LCD device accordingto one embodiment of the present invention;

[0029]FIG. 3B is a view showing a structure of an LCD device accordingto another embodiment of the present invention;

[0030]FIG. 3C is a view showing a structure of an LCD device accordingto still another embodiment of the present invention; and

[0031]FIG. 4 is a view showing an example of liquid crystal panelsfabricated on a glass substrate according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings.

[0033] In the present invention, the efficiency of a glass substrate, onwhich liquid crystal panels are formed, is increased to improve thefabrication yield of the liquid crystal display (LCD) devices. For thispurpose, the margin of each of the liquid crystal panels on the glasssubstrate is minimized to produce a maximum number of liquid crystalpanels on a single glass substrate. The margin of the liquid crystalpanel can be minimized by reducing a dummy region on which shorting barsare formed, since it is generally difficult and undesirable to reducethe size of the displaying unit on which pixels are formed.

[0034] Conventionally, a gate shorting bar is formed in pairs and a datashorting bar is formed in pairs. These shorting bars apply test signalsalternately to the respective gate line and the respective data line.However, in the present invention, the gate shorting bar and/or the datashorting bar is formed to be of a single bar. This reduces the area sizeof the dummy region on which the shorting bars are formed, and therebyminimizes the margin of the liquid crystal panel. Therefore, the size ofthe area occupied by a single liquid crystal panel on the glasssubstrate is reduced and, consequently, the entire glass substrate canbe used more efficiently to produce a maximum number of liquid crystalpanels. In one example, Mo/AlNd having low resistance is used as theshorting bars.

[0035] Hereinafter, the LCD device according to the embodiments of thepresent invention will be described in detail with reference to FIGS.3A-4.

[0036]FIG. 3A is a view showing an LCD device according to oneembodiment of the present invention. As shown therein, a displaying unit102 of a liquid crystal panel 101 includes a plurality of pixel areasdefined by a plurality of gate lines 103 and data lines 105. Thin filmtransistors (TFTs) 107 connected to the gate lines 103 and the datalines 105 are formed in respective pixel areas. A gate pad 112 and adata pad 114 are formed on ends of each gate line 103 and each data line105. Accordingly, a channel layer is formed in the respective thin filmtransistor as a scan signal is applied through the corresponding gatepad 112 from a gate driving IC (not shown). A data signal is alsoapplied from a data driving IC (not shown) to the corresponding pixelelectrode 109 formed in the pixel area, through the data pad 114 andsource/drain electrodes of the TFT.

[0037] A single gate shorting bar 118 for all the gate lines 103 and apair of data shorting bars 116 a and 116 b for all the data lines 105are connected to the gate pads 112 and the data pads 114, respectively.Here, the gate shorting bar 118 is connected to all the gate pads 112,whereas a first data shorting bar 116 a is connected to odd data pads114 and a second data shorting bar 116 b is connected to even data pads114.

[0038] The gate shorting bar 118 and the data shorting bars 116 a and116 b are all connected to a test signal generating unit 120. When thetest signal generating unit 120 generate and outputs at least one gatetest signal to the gate shorting bar 118, this gate test signal isapplied to the gate electrodes of the thin film transistors 107 throughthe respective gate pads 112. On the other hand, when the test signalgenerating unit 120 generates and outputs at least one data test signalto each of the data shorting bars 116 a and 116 b, the data test signalsare passed through the respective data pads 114 and the source/drainelectrodes of the thin film transistors 107 and applied to the pixelelectrodes 109 appropriately.

[0039] A voltage difference generated in a pixel electrode due to theapplied gate/data test signal is detected using a sensor for detectingsuch a voltage such as a potential sensor. As a result, an error ordefect in each thin film transistor can be inspected effectively.

[0040] In one embodiment, the data shorting bars 116 a and 116 b aremade of, e.g., metal Cr, which may be the same material used to formsource/drain electrodes. The gate shorting bar 118 is mainly made of,e.g., Mo/AlNd; however, other metals may be used. The Mo/AlNd has alower resistance than Cr, and therefore, the generation of a signaldelay caused by a resistance difference on the entire liquid crystalpanel is prevented.

[0041] As described above, the area occupied by the gate shorting bar118 can be reduced significantly by forming only one gate shorting bar18 as compared to the multiple gate shorting bars. Consequently, thesize of the liquid crystal panel 101 can be reduced. In strictlyspeaking, the reduced area of the liquid crystal 101 is caused not byreducing the area of the displaying unit 102 of the panel 101, but byreducing the size of the dummy region in which the shorting bars areformed. Since the margin of the liquid crystal panel can be reduced byreducing the dummy region size, a greater number of liquid crystalpanels or larger liquid crystal panels can be formed on a single glasssubstrate to improve the yield of the LCD devices.

[0042]FIG. 3B is a view of an LCD device including a liquid crystalpanel 201 with a displaying unit 202 according to another embodiment ofthe present invention. In this embodiment, the LCD device includes asingle data shorting bar 216 and a pair of gate shorting bars 218 a and218 b. As shown in FIG. 3B, the gate shorting bars 218 a and 218 b applythe gate test signal(s) to the gate lines 203 in odd numbers and evennumbers alternately. In this case, the two gate shorting bars 218 a and218 b and the data shorting bar 216 are all connected to the test signalgenerating unit 220. The test signal generating unit 220 generates andoutputs corresponding test signals to the shorting bars 216, 218 a and218 b coupled to gate pads 212, data pads 214 and pixel electrodes 209.

[0043] In this embodiment, the gate shorting bars 218 a and 218 b aremainly made of, e.g., Cr, and the data shorting bar 216 is made of,e.g., Mo/AlNd. However, other metals may be used.

[0044]FIG. 3C is a view of an LCD device including a liquid crystalpanel 301 with a displaying unit 302 and pixel electrodes 309 accordingto another embodiment of the present invention. In this embodiment, asingle gate shorting bar 318 and a single data shorting bar 316 areprovided in the liquid crystal panel 301. As shown in FIG. 3C, the gateshorting bar 318 is connected to each of gate pads 312, and the datashorting bar 316 is connected to each of data pads 314. Therefore, thesize of the dummy region of the liquid crystal panel 301, on which thegate shorting bar 318 and the data shorting bar 316 are formed, can bereduced further, so that the margin of the liquid crystal panel can bereduced. In this embodiment, the gate shorting bar 318 and the datashorting bar 316 are made of, e.g., Mo/AlNd; however, other metals maybe used.

[0045]FIG. 4 shows an example of a glass substrate on which a pluralityof liquid crystal panels constructed as above are formed according to anembodiment of the present invention. The formation of multiple liquidcrystal panels on a single glass substrate will be described as takingan example of the liquid crystal panel shown in FIG. 3C. As shown inFIG. 4, a plurality of liquid crystal panels 301 are formed on a glasssubstrate 330. Each of the liquid crystal panels 301 comprises adisplaying unit 302 on which pixels are formed and a dummy region 304 inwhich the shorting bars 316 and 318 are formed. In this example, thegate shorting bar 318 and the data shorting bar 316 are formed in thedummy region as single bars, respectively. Therefore, the size of thedummy region can be reduced significantly as compared to the generaldummy region shown in FIG. 2. That is, the liquid crystal panel shown inFIG. 2 has a dummy region with the lengths of ‘a’ and ‘b’. However, eachliquid crystal panel shown in FIG. 4 has a dummy region with the lengthsof ‘c’ and ‘d’, which are shorter than ‘a’ and ‘b’, respectively.Therefore, the margin of each liquid crystal display device is reducedas much as the difference a-c and b-d, respectively.

[0046] In this manner, an extra space is created on the glass substrate330 as much as the reduced margin. Thus, a greater number of liquidcrystal panels or larger liquid crystal panels can be formed on theglass substrate 330. This maximizes the usage efficiency of the glasssubstrate.

[0047] As described above, according to the present invention, the gateshorting bar and/or the data shorting bar formed in the dummy region ofthe liquid crystal panel and used to inspect the thin film transistorsis made as a single bar respectively using Mo/AlNd having lowresistance. Thus, the margin of the liquid crystal panel can beminimized. Further, a greater number of liquid crystal panels or largerliquid crystal panels can be formed on a single glass substrate andthus, the usage efficiency of the glass substrate can be improvedgreatly.

[0048] As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

What is claimed is:
 1. A liquid crystal display (LCD) device comprising:a displaying unit including, a plurality of pixel areas defined by aplurality of gate lines and a plurality of data lines, a thin filmtransistor formed in each of the pixel areas and to be connected to apixel electrode formed in that pixel area, and at least one gate pad andat least one data pad formed on ends of the corresponding gate line anddata line; and a dummy region disposed in an outer portion of thedisplaying unit, and including a gate shorting bar and a data shortingbar which are connected to the gate pads and the data pads,respectively, to apply at least one test signal to the thin filmtransistors, wherein at least one of the gate shorting bar and the datashorting bar is a single shorting bar.
 2. The device of claim 1, furthercomprising: a test signal generating unit connected to the gate shortingbar and the data shorting bar to apply the test signal.
 3. The device ofclaim 1, wherein each of the thin film transistors includes: a gateelectrode connected to the corresponding gate line and for receiving agate test signal input through the gate shorting bar; a gate insulatinglayer formed on the gate electrode; a semiconductor layer formed on thegate insulating layer and activated as the gate test signal is input tothe gate electrode; and source/drain electrodes formed on thesemiconductor layer for transmitting the gate test signal to thecorresponding pixel electrode as the semiconductor layer is activated.4. The device of claim 1, wherein the data shorting bar is a single barconnected to the data pads, and the gate shorting bar includes a firstgate shorting bar connected to odd gate pads and a second gate shortingbar connected to even gate pads.
 5. The device of claim 4, wherein thefirst and second gate shorting bars are made of Cr, and the datashorting bar is made of Mo/AlNd.
 6. The device of claim 1, wherein thegate shorting bar is a single bar connected to the gate pads, and thedata shorting bar includes a first data shorting bar connected to odddata pads and a second data shorting bar connected to even data pads. 7.The device of claim 6, wherein the first and second data shorting barsare made of Cr, and the gate shorting bar is made of Mo/AlNd.
 8. Thedevice of claim 1, wherein each of the gate shorting bar and the datashorting is a single bar.
 9. The device of claim 8, wherein the gateshorting bar and the data shorting bar are made of Mo/AlNd.
 10. Adisplay device comprising: a plurality of pixel areas defined by aplurality of gate lines and a plurality of data lines, and including athin film transistor formed in each of the pixel areas; a plurality ofgate pads coupled to the gate lines in an outer portion of the displaydevice; a plurality of data pads coupled to the data lines in the outerportion of the display device; and a dummy region disposed in the outerportion of the displaying device, and including a gate shorting bar anda data shorting bar which are connected to the gate pads and the datapads, respectively, to apply at least one test signal to the thin filmtransistors, wherein at least one of the gate shorting bar and the datashorting bar is a single shorting bar.
 11. The device of claim 10,further comprising: a test signal generating unit connected to the gateshorting bar and the data shorting bar to apply the test signal.
 12. Thedevice of claim 10, wherein each of the thin film transistors includes:a gate electrode connected to the corresponding gate line and forreceiving a gate test signal input through the gate shorting bar; a gateinsulating layer formed on the gate electrode; a semiconductor layerformed on the gate insulating layer and activated as the gate testsignal is input to the gate electrode; and source/drain electrodesformed on the semiconductor layer for transmitting the gate test signalto a corresponding pixel electrode as the semiconductor layer isactivated.
 13. The device of claim 10, wherein the data shorting bar isa single bar connected to the data pads, and the gate shorting barincludes a first gate shorting bar connected to odd gate pads and asecond gate shorting bar connected to even gate pads.
 14. The device ofclaim 13, wherein the first and second gate shorting bars are made ofCr, and the data shorting bar is made of Mo/AlNd.
 15. The device ofclaim 10, wherein the gate shorting bar is a single bar connected to thegate pads, and the data shorting bar includes a first data shorting barconnected to odd data pads and a second data shorting bar connected toeven data pads.
 16. The device of claim 15, wherein the first and seconddata shorting bars are made of Cr, and the gate shorting bar is made ofMo/AlNd.
 17. The device of claim 10, wherein each of the gate shortingbar and the data shorting is a single bar.
 18. The device of claim 17,wherein the gate shorting bar and the data shorting bar are made ofMo/AlNd.